问题详情

Which of the following is NOT an effective way for the astronauts to treat the ailments they have？

A．To eat vitamin D to strengthen the bones.

B．To have some blood let out to reduce iron.

C．To take exercises to relieve the back pain.

D．To have folate acid to improve the vision.

请帮忙给出正确答案和分析，谢谢！